JPWO2018105202A1 - Solar cell module - Google Patents

Abstract

The solar cell module (200) includes a solar cell string in which a plurality of back junction solar cells (102, 103, 104) are electrically connected by wiring members (83, 84). A light-transmitting light-receiving surface protective material (91) is disposed on the light-receiving surface side of the solar cell string, and a back surface protective material (92) is disposed on the back surface of the solar cell string. The wiring member is a braided wire having a flat cross-sectional shape composed of a plurality of metal wires, and the first main surface of the wiring member is connected to the metal electrode of the back junction solar cell. The wiring material is provided with a conductive black layer on the entire first main surface.

Description

  The present invention relates to a solar cell module.

  A solar cell using a crystalline semiconductor substrate such as a single crystal silicon substrate or a polycrystalline silicon substrate has a small area of one substrate. Therefore, in practical use, a plurality of solar cells are electrically connected and modularized. The output is increased. By connecting a wiring material made of metal foil or the like to the electrode of the solar cell via solder, a conductive adhesive or the like, electrical connection between adjacent solar cells is performed. A solar cell module is obtained by sealing a solar cell string to which a plurality of solar cells are connected via a wiring material between a light-receiving surface protective material and a back surface protective material.

  Since the back junction solar cell is not provided with a metal electrode on the light receiving surface, it is black when viewed from the light receiving surface side. In modularization of a back junction solar cell, electrodes on the back surface of adjacent solar cells are electrically connected by a wiring material.

  When a black sheet is used as a back surface protection material in a solar cell module using a back junction solar cell, when the solar cell module is viewed from the light receiving surface, the gap between the solar cell and the solar cell is unified in black, and the design Sexuality is enhanced. On the other hand, since the wiring material connecting adjacent solar cells has a metallic luster, when a solar cell module is installed on the roof or wall of a building, reflected light of sunlight irradiated on the wiring material is visually recognized, and the design property May be damaged.

  In Patent Document 1, it is proposed that a portion exposed on the light receiving surface side of the wiring material is covered with a colored resin layer to suppress a decrease in design properties due to the metallic luster of the wiring material. In Patent Document 2, by providing a shield made of an insulating tape or the like between adjacent solar cells, the visual recognition of the wiring material from the light receiving surface side is blocked and the design of the module is improved.

JP 2010-87011 A Special table 2008-502149 gazette

  When the wiring material is covered with an insulating resin layer as proposed in Patent Document 1, the non-connection portion with the solar cell electrode is selectively covered, and the connection portion with the solar cell electrode is covered. In order to prevent this, it is necessary to pattern the resin layer on the wiring material. Further, when the wiring member and the solar cell are connected, alignment is necessary so that the portion not covered with the resin layer is connected to the electrode of the solar cell. For this reason, an increase in the manufacturing cost of the wiring material, an increase in the number of man-hours for alignment when connecting the wiring material, a decrease in the yield of the wiring material and the solar cell module, and the like become problems.

  In the configuration in which the shield is disposed between adjacent solar cells as in Patent Document 2, the shield is sandwiched between the solar cell and the wiring member at the end of the solar cell. Therefore, the output of the solar cell module may decrease due to the decrease in the contact area between the electrode of the solar cell and the wiring material, the bending stress of the wiring material, etc. Become.

  In view of the above, an object of the present invention is to provide a solar cell module that is unified in black as a whole when viewed from the light receiving surface, has high designability, suppresses a decrease in output due to a temperature change or the like, and has excellent durability. .

  The solar cell module of the present invention includes a solar cell string in which a plurality of solar cells having a light receiving surface and a back surface are electrically connected by a wiring material. In the solar cell string, the metal electrode provided on the back surface of the solar cell and the first main surface of the wiring member are connected by, for example, solder. A light-transmitting light-receiving surface protective material is disposed on the light-receiving surface side of the solar cell string, and a back surface protective material is disposed on the back surface of the solar cell string. The solar cell string is sealed with a sealing material filled between the light-receiving surface protective material and the back surface protective material.

  The solar cell is a back junction solar cell that does not have a metal electrode on the light receiving surface and is provided with a metal electrode only on the back surface. The main surface on the light receiving surface side of the back surface protective material is black. The wiring member is a braided wire having a flat cross-sectional shape composed of a plurality of metal strands, and the first main surface of the wiring member is connected to the metal electrode of the solar cell. The wiring material is provided with a conductive black layer on the entire first main surface.

  As the material of the metal element wire of the wiring material, copper or a copper alloy is preferable. As the conductive black layer provided on the surface of the wiring material, a metal layer containing palladium is preferable. For example, the conductive black layer is provided on the surface of the wiring material by electroless plating.

  The solar cell module of the present invention is excellent in design because the entire surface is unified in black when viewed from the light receiving surface. Moreover, since the contact resistance between the electrode of the solar cell and the wiring material is small, the output characteristics are excellent. Furthermore, since the wiring material has flexibility, the solar cell module is excellent in temperature cycle durability.

It is typical sectional drawing of the solar cell module concerning one Embodiment. It is a top view of the back surface of a solar cell grid. It is a schematic perspective view of a solar cell string. It is a block diagram of the sample for contact resistance evaluation.

[Schematic configuration of solar cell module]
FIG. 1 is a schematic cross-sectional view of a solar cell module (hereinafter referred to as “module”) according to an embodiment. A module 200 shown in FIG. 1 includes a solar cell string in which a plurality of solar cells 102, 103, and 104 (hereinafter referred to as “cells”) are electrically connected via wiring members 83 and 84.

  A light receiving surface protective material 91 is provided on the light receiving surface side (upper side in FIG. 1) of the solar cell string, and a back surface protective material 92 is provided on the back surface side (lower side in FIG. 1). In the module 200, the solar cell string is sealed by filling the sealing material 95 between the protective materials 91 and 92.

  As the cell, a back junction solar cell (back junction cell) is used. The back junction cell includes a p-type semiconductor layer and an n-type semiconductor layer on the back side of a semiconductor substrate such as crystalline silicon, and a metal electrode is provided on each of the p-type semiconductor layer and the n-type semiconductor layer. The metal electrode can be formed by a known method such as printing or plating. For example, an Ag electrode formed by screen printing of Ag paste, a copper plating electrode formed by electrolytic plating, or the like is preferably used.

  The back junction cell does not have a metal electrode on the light receiving surface of the semiconductor substrate, and collects photocarriers (holes and electrons) generated on the semiconductor substrate by a metal electrode provided on the back side of the semiconductor substrate. Since the back junction cell does not have a metal electrode on the light receiving surface, the entire surface of the cell is unified in black when viewed from the light receiving surface side, and is excellent in design. The shape of the cell is not particularly limited, but is generally rectangular in plan view. A rectangle includes a square and a rectangle. The “rectangular shape” does not need to be a perfect square or rectangle. For example, the shape of the semiconductor substrate may be a semi-square type (a rectangular corner having a rounded corner or a notch). Good.

  In order to increase the amount of light taken into the semiconductor substrate and improve the conversion efficiency, it is preferable that the light receiving surface of the cell is provided with an uneven structure. The uneven shape is preferably a quadrangular pyramid shape (pyramid shape). The pyramidal concavo-convex structure is formed, for example, by subjecting the surface of a single crystal silicon substrate to anisotropic etching. The height of the unevenness provided on the light receiving surface of the cell is, for example, about 0.5 to 10 μm, and preferably about 1 to 5 μm. An uneven structure may also be provided on the back surface of the cell.

  FIG. 2 is a plan view of the back side of a solar cell grid in which a plurality of back junction cells are arranged in a grid. In the solar cell grid 180, the solar cell strings 100, 110, 120 in which a plurality of cells are connected along the first direction (x direction) are arranged along the second direction (y direction) orthogonal to the first direction. Is arranged in.

  The solar cell string 100 includes a plurality of cells 101 to 105 arranged in the first direction. A solar cell string is formed by electrically connecting the electrodes provided on the back side of the cell via the wiring members 82 to 85. A plurality of cells are connected in series by connecting the p-side electrode of one of the two adjacent cells and the n-side electrode of the other cell via a wiring material. The cells can be connected in parallel by connecting the n-side electrodes or the p-side electrodes of adjacent cells.

  In the solar cell string 100, the wiring member 81 disposed at one end portion in the first direction includes a lead wire 81a that can be connected to an external circuit. The wiring member 86 disposed at the other end in the first direction is connected to the solar cell string 110 adjacent in the second direction.

  FIG. 3 is a schematic perspective view of the solar cell string 100. In FIG. 3, adjacent cells are connected by two wiring members. The number of wiring members arranged between adjacent cells is appropriately set according to the electrode pattern shape of the cells.

  In the solar cell module, the portions 831 and 841 located in the gaps between the adjacent solar cells of the wiring members 83 and 84 are exposed to the light receiving surface side, and thus are visible from the outside. As will be described in detail below, by using a wiring material having at least a light receiving surface side of the wiring material, metal reflection of the wiring material is reduced, and the exposed part of the wiring material and the cell are unified, and the solar cell module Designability is improved.

[Wiring material]
The wiring material has a first main surface, a second main surface, and a side surface. The wiring member is a braided wire having a flat cross-sectional shape composed of a plurality of metal wires, and a conductive black layer is provided on the entire surface of the first main surface. In the solar cell string, the wiring material is arranged so that the first main surface is on the light receiving surface side, and the first main surface of the wiring material is connected to the back electrode of the cell.

  The width of the wiring material is, for example, about 1 mm to 5 mm, and the thickness of the wiring material is, for example, about 50 μm to 500 μm. The diameter of the metal strand which comprises a braided wire is about 10-200 micrometers, for example. The number of metal strands constituting the braided wire is about 10 to 500.

  In the back junction cell, since the back surfaces of adjacent cells are connected to each other by the wiring material, shadowing loss does not cause a problem even when the width (area) of the wiring material is large. By increasing the width of the wiring material as a flat shape, the contact area between the cell and the wiring material can be increased, and the contact resistance can be reduced. Further, by increasing the contact area between the cell and the wiring material, the adhesion reliability between the cell and the wiring material is increased, and the durability of the solar cell module is improved.

  When the contact area between a plate-like wiring material used in a general module and a cell increases, a connection failure such as peeling of the wiring material occurs due to the difference in coefficient of linear expansion between the wiring material and the cell due to temperature change. Cheap. On the other hand, a braided wire made of a plurality of strands is flexible and stretchable, so that stress resulting from the difference in linear expansion accompanying temperature change can be absorbed and dissipated by the wiring material. Therefore, even when the contact area between the cell and the wiring material is increased, high adhesion reliability can be maintained.

  The braided wire having a flat cross-sectional shape may be formed by knitting a plurality of metal strands so as to have a flat shape, and the braided wire obtained by knitting a plurality of strands into a cylindrical shape is converted into a flat cross-sectional shape by rolling. Also good. As for the method of knitting the metal wire, flat knitting, single knitting, double knitting, triple knitting, denby knitting, cord knitting, atlas knitting, chain knitting, crochet, fourth knitting, sixth knitting, eighth knitting Examples include knitting, netting, iron wire, braiding, right tying, left tying, warp tying, weft tying, diagonal knitting, rubber knitting, koko knitting, knitting knitting, garter knitting and the like.

  The metal material which comprises a metal strand will not be specifically limited if it is electroconductivity. In order to reduce electrical loss due to the resistance of the wiring material, it is preferable that the material of the wiring material has a low resistivity. Among these, copper or a copper alloy containing copper as a main component is preferable because the material is low cost.

(Conductive black layer)
The wiring material is provided with a conductive black layer on at least the entire first main surface. By providing the conductive black layer on the first main surface, light reflection at the portions 831 and 841 located in the gaps between the cells and exposed to the light receiving surface is reduced. Therefore, when the module is viewed from the light receiving surface side, the exposed portion of the wiring material and the cell color are unified.

  From the viewpoint of unifying the entire module in black, the visible light reflectance of the first main surface of the wiring member is preferably as small as the reflectance of the cell light receiving surface, and preferably 10% or less. By providing the black layer described in this specification, a desired visible light reflectance can be realized. On the other hand, since the black layer is made of a conductive material containing a metal, it is difficult to completely eliminate surface reflection.

  Since the surface of the braided wire composed of a plurality of metal strands has irregularities due to the shape of the metal strands (generally circular in section), light is irregularly reflected on the surface of the wiring material. Therefore, the light reflected on the surface of the wiring member is visually recognized as haze-scattered light by the viewer on the light receiving surface side, and the reflected light with metallic luster is hardly visually recognized. Therefore, even if the light reflection at the wiring material cannot be completely suppressed, the designability due to the reflected light from the wiring material is unlikely to occur. If the light receiving surface of the cell is uneven, the reflected light on the light receiving surface of the cell and the reflected light on the first main surface of the wiring material consisting of the braided wire are approximated. The reflected light is inconspicuous and the design of the module is improved.

  On the first main surface of the wiring members 83 and 84, a conductive black layer is provided on the first main surface not only in the exposed portions 831 and 841 between adjacent cells but also in the connection portions with the cells. Since the black layer provided for preventing light reflection has conductivity, the contact resistance between the cell electrode and the wiring material is small, and the power generation loss of the module can be reduced. Since the conductive black layer is provided on the entire first main surface of the wiring material, strict alignment is not required when connecting the cell and the wiring material. Therefore, productivity and yield of the solar cell module can be improved.

  A conductive black layer may also be provided on the side surface and the second main surface of the wiring member in the same manner as the first main surface. A non-blackening region where no conductive black layer is provided may be present in a portion not exposed on the surface of the wiring material.

  A braided wire having a conductive black layer can be obtained, for example, by subjecting a braided wire made of a metal strand to a conductive blackening treatment. A metal wire subjected to conductive blackening treatment may be knitted to form a braided wire. For the formation of the conductive black layer, for example, a dry process such as a sputtering method, a CVD method or a vacuum deposition method; a wet process such as application of a metal paste material, electrolytic plating or electroless plating (self-catalytic plating or displacement plating) is applied. Is possible.

  As the material of the conductive black layer provided on the surface of the wiring material, an alloy of copper and nickel, chromium, zinc, palladium or the like, metal palladium or palladium alloy, metal oxide, carbon nanotube or carbon in the metal, etc. The thing etc. which disperse | distributed black material are mentioned. Especially, since it is excellent in electroconductivity, adhesiveness with metal materials, such as copper, and wettability with respect to solder is high, it is preferable to provide the metal layer containing palladium as an electroconductive black layer.

  As a method of providing a metal layer containing palladium on a wiring material (or a metal element wire constituting the wiring material), electroless plating is preferable. As the electroless plating solution, for example, an aqueous solution containing a palladium salt, a halide ion, and a nitrogen-containing compound is used. The electroless plating solution is preferably an acidic aqueous solution having a pH of about 0 to 5.

  Examples of the palladium salt include palladium chloride, palladium sulfate, palladium oxide, palladium iodide, palladium bromide, palladium nitrate, palladium acetate, tetraammine palladium chloride, dinitrodiammine palladium, dichlorodiethylenediamine palladium, and the like. The palladium concentration in the electroless plating solution is preferably about 0.001 to 5 g / L.

  Examples of halide ions include chloride ions, bromide ions, and iodide ions, with chloride ions being preferred. What is a halide ion source for containing halide ions in an electroless plating solution? Hydrohalic acids such as hydrochloric acid, hydrobromic acid and hydroiodic acid; alkali metal salts such as sodium chloride and potassium bromide; alkaline earth metal salts such as magnesium chloride and calcium iodide; ammonium chloride and ammonium bromide And ammonium halides. The halide ion concentration in the electroless plating solution is preferably about 1 to 300 g / L.

  As the nitrogen-containing compound, polyamines such as alkylene diamine, polyalkylene polyamine, polyamide polyamine, and crosslinked product of polyamide polyamine are preferable. The content of the nitrogen-containing compound in the electroless plating solution is preferably about 0.01 to 200 g / L.

  A conductive black layer (electroless palladium plating layer) containing palladium is provided by bringing the electroless plating solution into contact with the material to be blackened (wiring material or metal wire). For example, the electroless plating solution may be brought into contact with the blackening treatment material by immersing the blackening treatment material in the electroless plating solution. An electroless plating solution may be sprayed on the surface of the blackening treatment material.

  When a braided wire knitted with metal strands is immersed in an electroless plating solution, a conductive black layer is provided on the entire surface of the first main surface, side surface and second main surface, that is, the entire exposed portion of the surface of the metal strand. The obtained wiring material is obtained. When the electroless plating solution sufficiently penetrates into the braided wire, a conductive black layer is also provided on the portion of the metal wire that is not exposed on the surface of the wiring material.

  On the other hand, when the braided wire has a high knitting density or when the wettability of the metal strands to the electroless plating solution is small, the electroless plating solution is difficult to penetrate inside and is exposed on the braided wire surface of the metal strands. The part which does not become a non-blackening process area | region where the electroconductive black layer is not provided. For the purpose of unifying the entire surface of the solar cell module in black, it is sufficient that a black layer is provided in a region (first main surface of the exposed portions 831 and 841) that is visible from the outside of the wiring member. The portion of the wire that is not exposed on the surface of the wiring material may be a blackened region or a non-blackened region.

  The treatment temperature for electroless plating is, for example, preferably about 10 to 60 ° C, and more preferably about 20 to 50 ° C. The treatment time is preferably about 10 seconds to 10 minutes, for example.

  Before performing the conductive blackening treatment by electroless plating, a degreasing treatment, an acid treatment, or the like may be performed as necessary for the purpose of removing dirt or oxide film on the surface of the material to be plated. The plating material after electroless plating may be washed and dried as necessary.

[Formation of solar cell module]
In the production of the module, first, a wiring material composed of a back junction cell and a blackened braided wire is prepared, and adjacent cells are connected to each other via the wiring material to produce a solar cell string. . The back electrode of the cell and the first main surface of the wiring member are connected via a conductive connection material such as solder, a conductive film, or a conductive paste.

  When solder is used as the conductive connection material, a material obtained by welding solder in advance on the first main surface of the wiring material or on the electrode of the cell may be used. When solder is fused in advance onto the first main surface of the wiring material, if the solder adheres to the exposed portions 831 and 841 between adjacent cells, the metallic luster of the solder is visually recognized from the light receiving surface of the module, and the design property is improved. descend.

  When the solder is previously fused on the first main surface of the wiring material, the solder fusion area on the wiring material is adjusted so that the solder does not protrude into the visual recognition area, and the wiring material is connected when the solder is connected. Must be strictly aligned with the cell. On the other hand, the method of providing solder on the electrode of the cell and connecting the wiring material thereon does not require exact alignment for the purpose of preventing the solder from protruding to the exposed portion of the wiring material between the cells. Therefore, it is preferable to provide fusion solder, solder paste, or the like on the electrode of the cell to connect the electrode and the wiring material.

  When the cell and the wiring material are connected by soldering, a solder connection pad may be arranged at a portion where the finger electrodes on the peripheral edge in the cell surface are gathered, and the wiring material may be connected thereon. In a wiring material composed of a braided wire of a plurality of metal strands, molten solder tends to stay in the space between the metal strands due to capillary action. Therefore, the spread of the solder is suppressed, and the solder does not easily protrude from the exposed portion of the wiring material between the cells. Since it is difficult for the solder to spread, the area of the solder connection pad may be reduced.

  Since the wiring material made of a plate-like metal member used for a general module is rigid, if the area of the solder connection pad is reduced, it may be difficult to align the wiring material and the solder connection pad. On the other hand, since the braided wire made of a plurality of strands is flexible and stretchable, even when a positional deviation occurs between adjacent cells, the wiring material is aligned on the solder connection pad by bending the wiring material. Can be implemented.

  Since the wiring member made of the braided wire is flexible and stretchable, it can be used for alignment in the connection direction (x direction) of the strings. Wiring material made of braided wire is also bent in the cell thickness direction (z direction), so it is possible to dissipate stress in the thickness direction and connect multiple cells even when the cells are warped Problems such as breakage when handling a subsequent string can be suppressed.

  A solar cell string in which a plurality of cells are connected via a wiring material is sandwiched between a light-receiving surface protection material 91 and a back surface protection material 92 via a sealing material 95 to form a solar cell module. It is preferable to cure the encapsulant by heating a laminated body in which the light-receiving surface sealing material, the solar cell string, the back surface sealing material, and the back surface protecting material are sequentially placed on the light-receiving surface protection material. . Prior to sealing, a plurality of solar cell strings may be connected to form a solar cell grid as shown in FIG.

  As the sealing material 95, a polyethylene resin composition mainly composed of an olefin elastomer, polypropylene, ethylene / α-olefin copolymer, ethylene / vinyl acetate copolymer (EVA), ethylene / vinyl acetate / triallyl. It is preferable to use a transparent resin such as isocyanurate (EVAT), polyvinyl butyrate (PVB), silicon, urethane, acrylic, or epoxy. The materials of the sealing material on the light receiving surface side and the back surface side may be the same or different.

  The light receiving surface protecting member 91 is light transmissive, and glass, transparent plastic, or the like is used. As the back surface protective material 92, a black sheet whose main surface on the light receiving surface side is black is used. By using a black sheet as the back surface protection material, in addition to the cells, both the wiring material and the back surface protection material exposed between adjacent cells are unified in black, so the entire surface is unified in black and highly designed A module is obtained.

  As the black sheet, for example, a sheet including a black resin layer is used. The black resin layer has a visible light absorptivity and mainly absorbs visible light having a wavelength of 800 nm or less. The visible light transmittance of the black resin layer is preferably 10% or less. As the black resin layer, a resin composition containing a polyolefin resin, a polyester resin, an acrylic resin, a fluororesin, a thermoplastic resin such as an ethylene / vinyl acetate resin, and a colorant such as a pigment or a dye is preferably used.

  The black sheet used as the back surface protective material 92 may absorb visible light while having infrared reflectivity. By using a back surface protective material having infrared reflectivity, infrared light contained in light passing through a gap between adjacent cells or light transmitted through the cells can be reflected to the light receiving surface side and used for power generation. As a black sheet which has infrared reflectivity, what laminated | stacked the black resin layer and the infrared reflective layer, and the thing containing the pigment which has infrared reflectivity in a black resin layer are mentioned. As the infrared reflective layer, a resin layer made of a resin composition containing a white pigment having infrared reflectivity such as titanium oxide, an infrared reflective metal foil (for example, aluminum, silver), or the like is used.

  As described above, by using a wiring material made of braided wire, tolerance of cell electrode patterning accuracy and alignment accuracy can be increased, and damage during handling can be suppressed, so that module manufacturing efficiency and yield can be reduced. It can be improved. Further, as described above, in the completed module, the stress caused by the difference in the linear expansion coefficient due to the temperature change can be absorbed and dissipated by the wiring material made of the braided wire. Therefore, even when subjected to a temperature cycle test, poor connection of wiring materials due to dimensional changes or the like hardly occurs, and a module having excellent durability can be obtained.

  Black wire is applied to a braided wire with a flat cross section (width: about 2 mm, thickness: about 200 μm) knitted from a total of 64 copper wires with a diameter of about 60 μm as a unit, and evaluation is carried out did.

[Solder wettability]
As Example 1, the above braided wire was immersed in an electroless palladium plating solution containing 0.5 g / L of palladium ("OPC Black Copper" manufactured by Okuno Pharmaceutical Co., Ltd.), and electroless plating was performed at room temperature. A braided wire having a conductive black layer on the entire surface was obtained. The strands inside the braided wire were not provided with a conductive black layer, and copper was exposed. The obtained braided wire had a black surface as a whole and exhibited good solder wettability similar to that of the braided wire before blackening treatment.

  The above braided wire was subjected to black chrome treatment example 2, black nickel treatment example 3 and black oxide treatment (formation of fine concavo-convex film of copper oxide) 4 by strong alkali boiling. Evaluation similar to Example 1 was performed. In Examples 2 to 4, the entire surface of the wiring material was black, but did not show solder wetting.

[Contact resistance]
As schematically shown in FIG. 4, 20 wiring members 401 to 420 were solder-connected at equal intervals in the length direction of a strip-shaped copper-plated film 450 having a width of 3 mm to prepare a contact resistance evaluation sample. One terminal of the two-terminal ohmmeter is brought into contact with the contact point 1 between the wiring material 401 and the copper plating film 450, and the other terminal is brought into contact with the contact point x between the other wiring material and the copper plating film, between two points. The resistance of was measured. The position where the other terminal is brought into contact is sequentially changed on the wiring members 402 to 420, the resistance is measured, the inter-terminal distance d and the resistance are plotted, and linear approximation is performed by the least square method. The contact resistance Rc was calculated from the resistance value 2Rc when the obtained approximate line was extrapolated to d = 0.

  The contact resistance when a plate-like copper foil having a width of 1.5 mm was used as the wiring material was 2.3 times that when the braided wire not subjected to blackening treatment was used as the wiring material. On the other hand, the contact resistance when using the braided wire subjected to the blackening treatment of Example 1 as the wiring material is 1.1 times that of the braided wire not subjected to the blackening treatment, and the contact resistance before and after the blackening treatment There was no significant change in resistance. As a result, the wiring material made of braided wire has lower contact resistance with the electrode material during solder connection than the plate-like wiring material, and the characteristics are maintained even in the braided wire that has been blackened with palladium. You can see that.

  From the above results, by using a wiring material having a conductive black layer containing palladium on the surface of a braided wire made of a plurality of metal strands, the cell and the wiring material are visually perceived when viewed from the light receiving surface side. It can be seen that a solar cell module can be obtained that is unified and has improved design, and that has a low contact resistance during solder connection and excellent durability.

101-105 solar cell (cell)
81-86 Wiring material 100, 110, 120 Solar cell string 91 Light-receiving surface protective material 92 Back surface protective material 95 Sealing material 200 Solar cell module

Claims (7)

A solar cell string in which a plurality of solar cells having a light-receiving surface and a back surface are electrically connected by a wiring material; a light-transmitting light-receiving surface protective material disposed on the light-receiving surface side of the solar cell string; A solar cell module comprising: a back surface protective material disposed on the back surface; and a sealing material provided between the light receiving surface protective material and the back surface protective material to seal the solar cell string,
The solar cell does not have a metal electrode on the light receiving surface, the metal electrode is provided only on the back surface,
The main surface on the light-receiving surface side of the back surface protective material is black,
The wiring material is a braided wire having a flat cross section made of a plurality of metal wires, and the first main surface of the wiring material is connected to the metal electrode of the solar cell,
The said wiring material is a solar cell module with which the electroconductive black layer is provided in the whole surface of the 1st main surface.   The solar cell module according to claim 1, wherein the conductive black layer is a metal layer containing palladium.   The solar cell module according to claim 1 or 2, wherein the metal element wire of the wiring member is made of copper or a copper alloy.   The solar cell module according to any one of claims 1 to 3, wherein the conductive black layer is an electroless plating layer provided on a surface of a metal strand.   The said wiring material is a solar cell module of any one of Claims 1-4 whose visible light reflectance of a 1st main surface is 10% or less.   The metal strand which comprises the said wiring material has the non-blackening process area | region in which the electroconductive black layer is not provided in the part which is not exposed to the surface of a wiring material. The solar cell module described. The solar cell module of any one of Claims 1-6 by which the metal electrode provided in the back surface of the solar cell and the 1st main surface of the said wiring material are solder-connected.

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